A thin, tightly adhering oxide skin (only a few molecules thick) that forms when steel is tempered at a low temperature, or for a short time, in air or a mildly oxidizing atmosphere. The color, which ranges from straw to blue depending on the thickness of ...

Fracture of a metal during quenching from elevated temperature. Most frequently observed in hardened carbon steel, alloy steel, or tool steel parts of high hardness and low toughness. Cracks often emanate from fillets, holes, corners, or other stress rais ...

The destruction of adhesion between a coating and the surface coated.

(1) The relationship between the current density at a point on a surface and its distance from the counter electrode. The greater the ratio of the surface resistivity shown by the electrode reaction to the volume resistivity of the electrolyte, the better ...

Foreign substance which comes from the environment, adhering to a surface of a material

The number of cycles of stress that can be sustained prior to failure under a stated test condition.

A network of checks or cracks appearing on the surface.

The rate of crack extension caused by constant-amplitude fatigue loading, expressed in terms of crack extension per cycle of load application.

A decrease in the polarization of an electrode; the elimination or reduction of polarization by physical or chemical means; depolarization results in increased corrosion.

The maximum current density that can be used to obtain a desired electrode reaction without undue interference such as from polarization.

See chemical vapor deposition, physical vapor deposition and sputtering.

A cell developed in an electrolyte resulting from electrical contact between two dissimilar metals. See galvanic corrosion.

The ratio of the electrochemical equivalent current density for a specific reaction to the total applied current density.

A substance that produces depolarization.

The current flowing to or from a unit area of an electrode surface, generally expressed as amps per sq ft or milliamperes per sq ft (also milliamps per sq cm, etc).

Separation of a solid accompanied by little or no macroscopic plastic deformation. Typically, brittle fracture occurs by rapid crack propagation with less expenditure of energy than for ductile fracture.

Numerous, very fine cracks in a coating or at the surface of a metal part. Checks may appear during processing or during service and are most often associated with thermal treatment or thermal cycling. Also called check marks. checking, or heat checks.

The difference between the actual electrode potential when appreciable electrolysis begins and the reversible electrode potential.

An imprecise term used to denote a treatment given cold-worked material to reduce its strength to a controlled level or to effect stress relief. To be meaningful, the type of material, the degree of cold work, and the time-temperature schedule must be sta ...

A pair of dissimilar conductors, commonly metals, in electrical contact. See also galvanic corrosion.